Measles in a Population with Religious Exemption to
Vaccination -- Colorado

On July 24, 1985, a 17-year-old camper at a Colorado camp
attended
by Christian Scientists developed measles. She had become infected
while traveling in California during the 2 weeks before her arrival
at
the camp. Twenty-five counsellors and 110 campers, aged 14-25
years,
attended the camp; all were unvaccinated, and all were exposed to
the
index patient. At the time the index patient was diagnosed with
measles, the exposed campers and counsellors were not yet
infectious.
After discussions with state health officials, it was decided that
quarantining the campers and staff at the facility would be
impractical for medical and logistical reasons, since the camp is
located in a remote part of Colorado with minimal nearby medical
facilities. Therefore, the camp was closed July 27, before any
secondary cases occurred.

The campers and staff were from 24 different states. All were
placed under quarantine orders in their home states, and
vaccination
of family contacts was offered through state health departments.
Few
of the families accepted immunization.

A total of 50 associated cases occurred. In the second
generation, 31 campers and three counsellors residing in 15 states
developed measles, an attack rate of 25.2% (Figure 3). The mean
age
of these patients was 14.6 years. In the third generation, 16
cases
were reported from eight states. All were in unimmunized household
contacts. No spread to the general community was documented. No
serious complications, hospitalizations, or deaths were reported.
Overall, California reported the largest number of cases (16
(31.4%));
Colorado reported six (11.8%).
Reported by Immunization Program, S Ferguson, PhD, State
Epidemiologist, Colorado Dept of Health; Div of Field Svcs,
Epidemiology Program Office, Div of Immunization, Center for
Prevention Svcs, CDC.

Editorial Note

Editorial Note: The high attack rate (25.2%) in this camp
population
reflects the rapidity of transmission and high susceptibility of
unimmunized persons. Usual control methods consisting of timely
immunization of susceptible contacts were not possible in this
situation because of the religious beliefs of the campers and their
families. Quarantine efforts by individual state health
departments
and cooperation by families of campers were apparently successful
in
limiting spread of disease into the community. In an outbreak
among
Christian Scientists at Principia College earlier this year,
quarantine at the school was used as a control measure. Although
transmission was sustained for at least 4 generations, there was no
spread to the community (1).

The cost of controlling the camp outbreak was borne primarily
by
the camp, which lost approximately $106,000 in income from
cancellation of an entire session, and by parents, who in many
cases
had to cancel other summer plans to accommodate the quarantine.
Furthermore, state health departments in 16 states had to implement
control measures to ensure that the measles cases imported into
their
states did not become foci of other outbreaks.

Although persons unvaccinated because of religious exemptions
comprise a small proportion of the total population, such persons
are
at increased risk of acquiring vaccine-preventable diseases and may
account for a large proportion of serious measles-associated
complications. For example, all three reported measles-related
deaths
in 1985 occurred during the measles outbreak at Principia College.

Persons with religious exemptions have accounted for a small
percentage of the total number of reported measles cases in the
United
States (2). However, they may play important roles in sustaining
or
initiating transmission of measles. Although no spread occurred
outside the religious groups in the Principia College and Colorado
outbreaks, persons with religious exemptions to vaccination have
developed disease that has spread to the general community. In one
such outbreak this year in Montana, a person with a religious
exemption was the index patient for an outbreak that involved 137
persons (3).

While most state school immunization laws allow exemptions on
the
basis of religious convictions, the data presented here illustrate
the
necessity of excluding persons with religious exemptions (as well
as
other unvaccinated individuals) from school and other environments
in
epidemic settings where contact with other susceptibles may occur.
This serves both to protect their own health and to minimize
transmission in the community.

References

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